Fischer-Tropsch products after hydrotreating and hydrocracking under typical conditions are generally devoid of olefins, alcohols, acids and other oxygenates. By themselves they are highly stable and when appropriate precautions are used they make excellent blend components for distillate fuels when used with petroleum-derived distillate fuels. When the oxygenates are left in the diesel fuel they can contribute to peroxide formation. This problem can be solved by the use of anti-oxidants as described in U.S. Patent Application Publication Nos. 20040152930 and 20040148850.
The naphtha product from a Fischer-Tropsch product consists of paraffins, olefins and oxygenates (alcohols, acids, and traces of other compounds). All compounds are predominantly linear (normal paraffins, linear olefins, linear alcohols etc.). The linear paraffins and especially the linear olefins are desirable for making ethylene in naphtha crackers. The alcohols and especially the acids are not desirable because the latter contributes to corrosion.
Technology to remove the alcohols and acids from Fisher-Tropsch condensates to make olefinic naphtha for ethylene production has been developed and is described in U.S. patent application Ser. Nos. 10/355,279 and 10/354,956.
However in some situations customers for distillate fuels would prefer not to have fuels that contain olefins. Thus it can be desirable to make a olefinic naphtha while simultaneously making a hydrogenated distillate fuel. This application addresses this combined need.